Telephone-transmitter



PATENTED JAN. 5, 1 904.

(LT. BENNETT.

TELEPHONE TRANSMITTER.

APPLICATION FILED NOV. 29. 1901.

10 MODEL.

UNITED STATES i'atented .Tanuar'y 5, 1904.

CHARLES F. BENNETT, OF WATERLOO, IOWA.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 748,690, dated January 5, 1904.

Y Application-filed November 29, 1901. Serial No. 84,083. (No model.)

To all whom it may concern.-

Be it known that I, CHARLES F. BENNETT, a citizen of the United States, residing at Waterloo, in the countyo'f Blackhawk and State of Iowa, have invented a certain new and. useful Improvement in Telephone-Transmitters, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a telephone-transmitter employing finely-divided conducting material, preferably granular carbon, as a variable-resists.nee medium between two electrodes which are adapted to partake of relative movement corresponding to sound-waves and to vary the resistance through the said medium in accordance therewith.

It is the object of myinvention to provide a telephone-transmitter of this type which is simple and compact in structure and which is so organized as to prevent packing of the granular carbon, a defect common in the ordinary form, and which will also constantly agitate the carbon when the device is in use and maintain it in a highly sensitive and efficient condition. 1

In accordance with my invention, therefore, I provide a suitable receptacle for the granular carbon or other finely-divided conducting material in which the floor or lower edge is substantially horizontal or elevated above the ordinary circular shape, so as "to provide a space or chamber in which there will be less crowding together and packing of its contents than in the usual form. I further provide the said floor or lower edge or the sides of the recess or chamber or the electrodes, or all of the said parts, with a series of inclined planes or serrations so arranged that the vibrations of the electrodes or receptacle and the jarring of the transmitter will tend to cause the continual changing of the relative positions of the granular contents of the receptacle and to thereby keep it stirred up and in a loose condition.

In the drawings, Figure l is a sectional elevation of a transmitter embodying my improvement. Fig.2 illustrates theconstruction V of the invention in detail. Fig. 3 is a side and edge view of one of the electrodes. Fig. 4

is a similar view showing one form of serrations applied thereto. Fig. 5 is another View showing a different form of the serrations. Fig. 6 is a side and edge view of one of the segmental mica plates used to form the outside of the lower part of the receptacle. Fig. 7 is a similar view of one form of block forming the bottom of the carbon-chamber. Fig. 8 is a side and edge view of the same, showing its upper edge serrated. Fig. 9 is a face view of the assembled receptacle with the first electrodes omitted. Fig. 10 is a. side and edge view of the feltring used to separate the mica rings; and Fig. 11 is a side view of the receptacle, showing the said first electrode in place.

In the figures the same letters, as far as may be, represent the same parts.

A is a case of any usual or desired form, having the front piece B secured thereto, upon which is mounted the usual mouthpiece C, this piece being adapted to be mounted upon an arm D or in any preferred manner. 7

A sound-receivin g diaphragm a is provided, as is usual in such instruments.

The receptacle for the carbon, which constitutes my invention, is formed, as shown in Figs. 1 and 2, by the ring 3), of felt or other suitable material, (more clearly shown in Fig. 7,) upon each side of which at its lower portion the mica segments '0 are adapted to be placed. These segments are shown in Fig. 6. Between these mica segments 0 the segmental block (1 is placed, the upper edge of which is adapted to form the lower horizontal edge or floor of the space or chamber in which the finelydivided carbon or other conducting 'material is placed. As shown in Figs. 1, 2,

8, and 9, the upper edge of this block may be transversely serrated or notched, or it may be otherwise serrated, or smooth, as shown in Fig. 7. The serrations are preferable, however, as tending to agitate and disturb the granular material and to keep it loose and in an. active state. ments 0 the rings e, also of mica, are placed, these being of the same outside diameter as the felt ring b, but having a slightly smaller internal diameter; Within the open space formed by the inner periphery of each of these rings e and the upper edge of the correspond- Outside of the mica seging segment 0 the front and back contactelectrodes f and f are adapted to fit, the lower edge of these electrodes being horizontal to fit the corresponding upper edge of segment 0, so that only the upper half or slighty more than the upper half of the circular area of the inner circle of the rings is covered.

The reason for this construction is so that they shall terminate above the horizontal edge of the fiber block din order that they may freely and relatively vibrate toward and from each other in the use of the transmitter. These electrodesf and f are mounted, preferably, in brass chambered blocks or disks g and g, the outer inturned edges of which press lightly against the faces of the mica rings e when the device is assembled ready for use. This arrangement permits a pistonlike movement of the electrodes with reference to the granular carbon-chamber. As shown in Fig. 1, the shell, block, or disk 9 is secured by means of a screw it to the sound receiving diaphragm a, while the rear'chamber g is secured by means of a threaded stud h to the back part of the case.

When the parts are assembled, as shown in Fig. 1, the finely-divided carbon or other conducting material is placed between the electrodesfand f and rests upon the upper and substantially horizontal edge of the block d, this block being preferably of fiber. This horizontal edge or floor of the receptacle tends to prevent the packing of the carbon, so usual in instruments of the ordinary construction in which the lower part of the chamber is circular, and therefore causes a wedginglike action of the granules therein. Figs. 9 and 11 show face views of the assembled instrument and chambered block g and electrode f, being omitted in Fig. 9. From these views the relative arrangement of the serrations and the horizontal edge of the carbon-chamber may be seen. While the u pper edge of this blockd may be made smooth and good results obtained, it is preferably formed with the serrations d, which serve to agitate the carbon or other finelydivided conducting material during the vibrations of the sound-receiving diaphragm a. These serrations or notches may be formed as desired, but are preferred as shown. In addition the electrodesfand f may have serrations formed thereon in a substantially vertical direction, as shown in Fig. 4. When so constructed, they will assist the block at in stirring up the granular carbon to keep it loose and prevent packing. As shown also in Fig. 5, the serrations on these electrodes may extend radially, in which case the tendency will be to cause a circulation of the granular carbon,which will thus be kept in activeandsensitivecondition. serrations may, in fact, be placed at any part of the wall of the chamber.

The circuit of the instrument, as shown in Fig. 1, is through the shell A, the disk or chambered block g, electrode f the granular carbon between the electrodes, the electrode inclined planes.

f, and front chambered block or disk 9 to the diaphragm a, from which the circuit may be continued in any desired manner.

While I have described the specific construction of the receptacle and its various parts, it will be understood that the same may be formed of anysuitable material and in any desired manner so far as the broad features of my invention are concerned, as these con tem plate, broadly, a carbon chamber or receptacle having its sides formed by the front and back electrodes of the i nstru mentand its lower edge being substantially horizontal, said lower edge of the chamber and said electrodes being provided with serrations in the form of It is likewise apparent that electrodes of other vmaterial may be used, that the block 61 may be made of fiber, carbon, or other material, and that the mica rings and segments, while preferable, may be replaced by any parts capable of performing the desired functions.

Having thus described my invention, what I claim is- 1. In a telephone-transmitter, a chamber for finely-divided material having its sides formed by the front and back electrodes of the instrument, the lower edge of the chamber being'horizontal and the faces of said electrodes and the said lower edge of the chamber being provided with serrations in the form of inclined planes, whereby the conducting material is agitated in the use of the instrument, substantially as described.

2. In a telephone-transmitter, the combination with two electrodes adapted to receive finely-divided conducting material between them, a portion of the front of one of said electrodes provided with serrations in the form of inclined planes in one or more directions whereby the conducting material is caused to circulate in the use of the instrument, substantially as described.

3. In a telephone-transmitter, the combination with a front electrode and a back electrode, said electrode being provided with radial serrations, of a block of carbon or suitable material adapted to form the floor or lower edge of the space containing the finelydivided conducting material, said block having its upper edge horizontal and provided with serrations, substantially as described.

4. In a telephone-transmitter, the combination with a front electrode and a back electrode, said electrodes being provided with radial serrations in the form of inclined planes, of a member of suitable material forming the floor of said chamber and being substantially horizontal, the said member having its upper edge provided with serrations, substantially as described.

5. In a telephone-transmitter, the combination with a front electrode and a back electrode, said electrodes being provided with serrations in the form of inclined planes radiating in one or more directions, of a member forming the floor of the chamber and being substantially horizontal, and granular carbon contained within said chamber between the electrodes and resting upon the floor, substantially as described.

6. In a telephone-transmitter, a receptacle for finely-divided conducting material, said receptacle having a substantially horizontal or straightfloor provided with a series of inclined planes to agitate and cause the circulation of the conducting material, substantially as described.

7. Ina telephone-transmitter, the combination with a front electrode and a back electrode, of a substantially horizontal fioor for the chamber formed between said electrodes and in which the carbon granules are adapted to be placed, the inner faces of said electrodes being provided with serrations in the form of inclined planes, said inclined planes serving when the transmitter is used for talking to agitate the granulations and cause a circulation thereof, whereby the same does not pack and is maintained in asensitive condition, substantially as described.

8. In a telephone-transmitter, the combina tion with two electrodes adapted to receive finely-divided conducting material between them to serve as the resistance-varying medium of the transmitter, the inner faces of said electrodes being provided with serrations in the form of inclined planes, said serrations serving to agitate the resistance-varying medium and to cause it to circulate to thereby prevent it packing and to always maintain it in sensitive and active condition, substantially as described.

9. In a telephone-transmitter, the combination with a pair of opposed electrodes adapted to partake of relative movement in the use of the instrument, a member having a substantially horizontal upper edge or face forming the door of the receptacle between said electrodes, granular carbon within said receptacle and resting upon said floor, said floor being provided with inclined serrations extending transversely thereof, and serving in the use of the instrument to cause a circulation of the carbon to thereby prevent its packing, substantially as described.

10. In a telephone-transmitter,the combination with opposed front and back electrodes substantially semicircular in outline, a circular ring surrounding said electrodes, a semicircular block carried by the said ring, the upper edge of said block being substantially horizontal and located adjacent the lower edges of the said electrodes, said horizontal edge forming the door of the receptacle between said electrodes for the finely-divided conducting material, substantially as described.

In witness whereof I have hereunto subscribed my name in the presence of two witnesses.

CHARLES F. BENNETT. Witnesses:

GRACE RoDAMAR, G. G. BICKLEY. 

